Container box for framed pellicle

ABSTRACT

There is provided a pellicle container for use in photolithography, with which no dust particles are deposited onto the pellicle contained therein, and contamination of the pellicle can be prevented and good condition is ensured. The present invention provides a pellicle container consisting of a container base on which a pellicle is mounted, and a covering body that covers the pellicle and latches with the container base by engagement together with the container base along the peripheral edges, wherein the pellicle is supported by inserting a frame supporting pin in the opening of a sleeve provided on the outside surface of the pellicle frame. Preferably, the container base is made from a plastic resin and a metal component is joined to the container base; the metal component fixedly connected to the container base is mechanically connected to a positioning component that positions the frame supporting pin that supports the pellicle; and an elastic member is disposed on the point of contact between the frame supporting pin that supports the pellicle and the pellicle frame. It is even more preferable that the container boase and the Icovering body are made of a plastic resin, and these have antistatic performance such that their surface resistivity is no higher than 1×10 12  ohms.

BACKGROUND OF THE INVENTION

The present invention relates to a container box for holding, storing, and transporting a photolithographic pellicle used to shield it against dust deposition in the manufacturing process of semiconductor devices, printed circuit boards, liquid crystal display panels, and the like.

In the manufacture of liquid crystal display panels, semiconductor devices such as integrated circuits, and others, a pattern is produced by light exposure of a semiconductor wafer or base glass plate for liquid crystal use, but if dust particles are deposited onto the photomask or reticle used here (hereinafter referred to simply as “photomask”), the dust particles will block or scatter the light, which is a problem in that the fidelity of patterning is lost.

For this reason, this work is usually performed in a clean room, but, even in a clean room of the highest class, it is difficult to keep the photomask in a completely dust-free condition. This problem is handled by mounting a framed pellicle as a dust shield to the photomask surface.

In this case, foreign matter will not be deposited directly to the surface of the photomask, but to the pellicle instead, so that, if the exposure light in lithography is focused on the pattern of the photomask, any foreign matter particles on the pellicle will not affect figelity of patterning.

Nevertheless, while a pellicle is indeed effective for preventing foreign matter from getting into the closed space formed by the photomask and pellicle once the pellicle has been applied, if any foreign matter has already deposited to the pellicle per se and is present inside the closed space, it becomes very difficult to prevent that foreign matter from being deposited to the photomask surface. Thus, there is an urgent need for some means to keep clean the pellicle container used for storage and transportation, in addition to the need for the pellicle per se to be very clean.

As discussed above, a pellicle container must offer performance that allows a pellicle to be kept clean during its storage and transportation, and to this end it is important to minimize possible sources of dust.

Factors related to generation of dust include the material, electrical properties, and cleanliness of the components constituting the pellicle container, contact between the components constituting the pellicle container, contact between the pellicle container and the pellicle, external friction on the pellicle container, and so on.

Therefore, it is necessary to take into account a variety of factors such as the material, strength, and electrical properties of the components constituting the pellicle container, the manner for fixedly securing the pellicle, and so on.

A typical pellicle container used for semiconductors is constituted by a container basein which the pellicle is placed, and a covering that secures the pellicle and latches with the container base by fitting together at the peripheral edges. Each of these components is made of a plastic resin, and the covering is transparent.

A number of methods have been proposed as ways to fix a pellicle to a pellicle container.

One of the securing ways is to hold down the pellicle by press-contacting at the top face of the pellicle frame with the inner surface of the covering (see Japanese Utility Model Publication H6-45965).

As indicated in Japanese Utility Model Publication H6-45965, an advantage in holding down the top face of the pellicle frame with the inner surface of the covering is that the pellicle frame is securedly supported by a simple component structure, but since the pellicle container is usually made of a plastic resin, it is susceptible to force from outside the container, and if the entire pellicle container should be distorted by an external force, for example, the pellicle frame may end up being moved by the so strong force, possibly leading to generation of dust particles or permanent deformation.

This problem is particularly serious with a pellicle for alarge size liquid crystal display panel whose length on one side is over 400 mm.

Another method that has been proposed is to increase the rigidity of the container box by introducing a rib structure (see Japanese Laid-Open Patent Application 2000-173887).

An advantage to a method such as that indicated in Japanese Laid-Open Patent Application 2000-173887, in which rigidity is increased by introducing a rib structure into the container body, is that there is little thermal deformation resulting from changes in the external air temperature during transportation by airplanes, trucks, or the like in a hot weather, but a drawback is that it is difficult to keep the distortion that occurs when the user takes up the container just at one end down in a cantilever manner to affect the pellicle.

Still another fixing method that has been proposed is to indirectly fix the pellicle frame by using a pressing member to fix a protective film that protects a pressure-sensitive adhesive material that has been applied to the pellicle (see Japanese Laid-Open Patent Application H11-052553).

An advantage to the method indicated in Japanese Laid-Open Patent Application 2000-173887, in which a pellicle frame is indirectly fixed by using a pressing member to fix a protective film that protects a pressure-sensitive adhesive material that has been applied to the pellicle, is that force from outside the pellicle container has little effect on the pellicle frame, but since the protective film is usually formed by coating with a releasing agent to facilitate its release from the pressure-sensitive adhesive, there is a possibility that the pellicle frame may come loose from the protective film as a result of vibrations during transportation.

If a high peel strength grade of release agent is used for the protective film to prevent this, it can lead to deformation of the pressure-sensitive adhesive when the protective film is peeled away from the adhesive, which is a problem in that when the pellicle is applied to a photomask, these deformed sites will not stick to the photomask, resulting in occurrence of an air passage.

SUMMARY OF THE INVENTION

The present invention was conceived in view of the above problems, and it is an object thereof to provide a photolithographic pellicle container with which no foreign particles will be deposited to the contained pellicle during storage, transportation, or operation, and contamination of the pellicle can be prevented to ensure keeping of the pellicle in a condition of good quality.

To solve the above problems, the present invention provides a pellicle container comprising a container base in which a pellicle is placed, and a covering body that covers the pellicle and latches with the container body by engageable with the container base around the peripheral edges, wherein the pellicle is fixedly secured in a position by inserting a frame supporting pin in an opening provided to the outside face of the pellicle frame. Preferably, the container base is made from a plastic resin and a metal component is joined to the container base; the metal component fixedly attached to the container base is mechanically connected to a positioning component that positions the frame supporting pin that supports the pellicle; and an elastic member is disposed on the point of contact between the frame supporting pin and the pellicle frame. It is even more preferable that the container body and the covering body are both made of a plastic resin, and that these have antistatic performance such that their surface resistivity is no does not exceed 1×10¹² ohms.

In the present invention, a pellicle frame can be securedly grasped while keeping contact points to the minimum, which reduces the likelihood of dust generation, and since the frame supporting pin is provided to a container body of increased rigidity, the pellicle is affected little by an external force. Further, in an embodiment in which the container base is made from a plastic resin and a metal component is joined to this container base, the light weight of the plastic resin can be taken advantage of while compensating for the distortion that is a drawback to plastic, allowing just the required portions to be capable of shape retention with respect to external forces.

In an embodiment in which a component that positions the frame supporting pin that supports the pellicle is mechanically connected to a metal component attached to the container base, the position of the pellicle can be kept constant during storage, transportation, and operation, which reduces generation of dust and deformation.

In an embodiment in which an elastic member is disposed at the part of the frame supporting pin supporting the pellicle that comes into contact with the pellicle frame, the influences of vibrations on the pellicle during storage, transportation, and operation can be reduced.

In an embodiment in which the container base and the covering body are both made from a plastic resin and antistatic performance is imparted such that their surface resisttivity is no higher than 1×10¹² ohms, a foreign matter deposition prevention effect can be obtained, such as preventing static electricity that is produced by friction with a packaging bag, which can be a particular problem with a container of a pellicle for large liquid crystal display panels.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross section of an embodiment of the pellicle container pertaining to the present invention;

FIG. 2 is an enlarged cross sectionall view showing the frame supporting part in an embodiment of the pellicle container pertaining to the present invention;

FIGS. 3A and 3B are a plan view and a cross sectional view, respectively, of the container base in an embodiment of the pellicle container pertaining to the present invention;

FIGS. 4A and 4B are a cross sectional view and a plan view of the bottom surface, respectively, of the container base of the inventive pellicle container; and

FIG. 5 is a cross sectional view of a pellicle container of the prior art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will now be described by making reference to the drawings, but the present invention is not limited to or by these embodiments.

FIG. 1 is a cross section of an embodiment of the pellicle container pertaining to the present invention, and FIG. 2 is an enlarged view thereof.

FIGS. 3A and 3B illustrate a plan view and a cross sectional view, respectively, of the container base with a framed pellicle mounted thereon in an embodiment of the pellicle container pertaining to the present invention. FIGS. 4A and 4B illustrate a cross sectional view and a bottom view, respectively, of the container base of the inventive pellicle container.

In FIG. 1, the pellicle container of the present invention is constituted by a container base 1, a covering body 2, frame support pins 3, pin fixing components or bosses 4, and reinforcing metal members 5.

Just as in a conventional pellicle container, a framed pellicle is mounted on a raised stand in the middle of the container base 1, and the covering body 2, which is engaged with the container base 1 by fitting together along the peripheral edges, is placed covering this to form a closed space.

When making the whole container having a lighter weight is taken into account, the container base and the covering body are preferably made from a plastic resin, but in the case of the container of a large pellicle for use in a liquid crystal display panels, deformation of the plastic members will have a particularly great influence on the product, and the reinforcing metal components 5 are joined to the bottom surface of the container base 1 to reduce warping.

It is preferable for antistatic performance to be imparted to the plastic used for the container base 1 and the covering body 2 in order to prevent the pellicle from becoming charged, which would cause dust deposition. This antistatic performance is preferably such that the surface resistivity is not higher than 1×10¹² ohms.

There are no particular limitations on the types of the plastic resin, but suitable examples include acrylic resins, polyethylene terephthalate resins, acrylonitrile-butadiene-styrene resins, polystyrene resins, polycarbonate resins, vinyl chloride resins, polypropylene resins, polyethylene resins, and acrylonitrile-ethylene-styrene esins.

As for way for imparting the antistatic property to the plastic resin, any known method is applicable provided that there is no particular problem relative to dust generation including the method blending a hydrophilic polymer into the base resin, coating of the plastic resin body with an electroconductive coating film, compounding of the base resin with an electroconductive material and so on.

Examples of the metallic material used for the reinforcing members include aluminum, stainless steels, carbon steels, copper, and brass. When the specific gravity and elastic modulus must be considered, aluminum is preferable.

As shown by the enlarged view in FIG. 2, a pellicle frame 6 is secured in the position by insertion of the frame supporting pins 3 into jig openings 10 provided on the outside surface of the frame. Preferably, an elastic member 8 is disposed at the distal end of each of the frame supporting pins 3 to grasp the pellicle frame with resilience.

The pin fixing components or bosses 4 serve to position the frame supporting pins 3, and if mechanically Iconnected with a screw bolt 9 or the like to the reinforcing metal components 5 on the bottom side of the container base, the positional accuracy of the frame supporting pins can be maintained even if the container base is distorted by thermal deformation or a force from outside the container.

Examples of the material of these elastic members include nitrile rubbers, styrene rubbers, silicone rubbers, fluorocarbon rubbers, chloroprene rubbers, polyurethane rubbers, tetrafluoroethylene resins, polyacrylic rubbers, and ethylene-propylene rubbers. From the standpoint of durability, silicone rubbers or tetrafluoroethylene rubbers are preferable. To control static electricity, an antistatic function may also be imparted to these materials.

The pellicle frame 6 must be fixed by the frame supporting pins 3 at than three or more positions, and preferably four or more positions including the positions near the four corners of the rectangular pellicle frame 6 as shown in FIG. 3A.

As shown in FIG. 4B, which is a plan view of the bottom of the container base, the reinforcing metal components 5 are disposed on the bottom surface of the container base to prevent deformation of the container base 1. The reinforcing metal components 5 are preferably mechanically connected to the pin fixing components 4. The desired effect can be expectedly the same even by using a single reinforcing metal component 5 alone, but the effect will be enhanced by connecting the reinforcing components running down and across each to the others.

In the following, a working example of the present invention will now be described, although the present invention is never limited thereby or thereto in any way.

WORKING EXAMPLE

The pellicle containers illustrated in the drawings were constructed.

The pellicle container had a structure mainly composed of the container base 1, which was prepared by vacuum forming of an antistatic ABS resin (Toyolac Parrel TP10 (trade name of Toray); surface resistivity of 5×10¹¹ ohms), and the covering body 2, which was prepared also by vacuum forming of an antistatic ABS resin (Toyolac Parrel TP10, supra); surface resistivity of 5×10¹¹ ohms). The reinforcing metal components 5, which were made from aluminum and had a cross section of 40×6 mm, were disposed on the bottom surface of the container base and five of the reinforcing metal components 5 were connected in the down and across directions as shown in FIG. 4B.

Furthermore, the reinforcing metal components 5 disposed on the bottom surface of the container base, and the pin fixing components 4 disposed on the upper surface of the container base were mechanically connected by M4 screw bolts to the container base intervening therebetween. The pin fixing components 4 and the frame supporting pins 3 were made from a PPS resin, and the frame supporting pins 3 were provided at four locations in the vicinities of the corners of the pellicle frame 6, as shown in FIG. 3A. The elastic members 8, which were made of a fluorocarbon rubber, were disposed at the distal ends of the frame supporting pins 3 to come into contact with the pellicle frame 6.

After completion of this pellicle container, one end surface of a pellicle frame 6 made from an aluminum alloy and having outer dimensions of 782×474×6 mm, was coated with a silicone-based pressure-sensitive adhesive (KR120, trade name by Shin-Etsu Chemical Co.) to serve as a pellicle membrane adhesive, and the other end surface was coated with the same pressure-sensitive adhesive (KR120, supra) to serve as the photomask adhesive. The adhesive layers were cured by heating. A pellicle membrane of a fluorocarbon polymer (Cytop, trade name by Asahi Glass Co.) having a thickness of about 4 μm as prepared by spin coating of a resin solution was spread over and adhesively bonded in a slack-free fshion to one adhesive-coated end surface of the frame 6 to complete the framed pellicle 7. This framed pellicle was housed in the pellicle container and subjected to a two-way air transportation test between Tokyo and Fukuoka followed by examination of the increment in the number of dust particles on the pellicle membrane before and after the air transportation.

The pellicle taken out of the pellicle container in a class 100 clean room was inspected in a dark room under illumination of 400000 lux to count the dust particles on the pellicle membrane. The result was that no increase was noted in the number of dust particles caused by the air transportation test. No deformation and damages could be detected in any parts of the framed pellicle. Further, the electrostatic charging on the pellicle membrane was measured with an instrument made by Ion System (Ion System/Model 775 California, USA), to find an electrostatic voltage of −0.1 kV.

COMPARATIVE EXAMPLE

The pellicle container shown in FIG. 5 was manufactured, which had a structure in which the top face of a conventional pellicle frame 6 was press-held with the inner surface of the covering body 2. The container base 1 and the covering body 2 were both made from an acrylic resin having a surface resistivity of at least 10¹⁸ ohms.

One end surface of a pellicle frame 6, made from an aluminum alloy and having outer dimensions of 782×474×6 mm was coated with a silicone-based pressure-sensitive adhesive (KR120, supra) to serve as the pellicle membrane adhesive, and the other end surface was coated with the same adhesive (KR120, supra) to serve as a photomask adhesive. The adhesive layers were cured by heating. A pellicle membrane of a fluorocarbon resin (Cytop, supra) prepared by spin coating of a ewaub solution as a pellicle membrane 7 having a thickness of about 4 μm was spread over and adhesively bonded to one of the adhesive-coated end surfaces of the pellicle frame 6 in a slack-free fashion to complete a framed pellicle which was housed in the above pellicle container and subjected to the air transportation test in the same manner as in the Example.

After the transportation test, the pellicle taken out of the pellicle container in a class 100 clean room was subjected to the dust particle counting test in the same manner as in the Example to find that the bumber of dust particles having a size of 10 μm or larger on the pellicle membrane was increased by 48. In addition, indentations, which were not found before the transportation test, were found in the membrane adhesive layer at the positions where the adhesive layer was press-contacted with the inner surface of the covering body 2. Further, the electrostatic charge measurements conducted in the same manner as in the Example gave a result that the electrostatic voltage on the pellicle membrane was −3.8 kV.

As is discussed above, with the present invention, no dust particles will be deposited onto the framed pellicle contained in the inventive pellicle container during storage, transportation, or operation, and contamination of the pellicle can be prevented and could be kept in a good dust-free condition over a length of time. 

1. A container of a photolithographic framed pellicle consisting of a container base and a covering body each engageable with the other along the peripheries to form a closed space therebetween, which is further provided with at least three pin sleeves fixedly connected onto the upper surface of the container base in such a fashion as to allow a pellicle frame-supporting pin inserted into the pin sleeve to reach a cavity formed in the frame of the framed pellicle when a framed pellicle is contained in the pellicle container.
 2. The pellicle container as claimed in claim 1 wherein the container base and the covering body are formed from a plastic resin and the pin sleeves are formed from a metallic material.
 3. The pellicle container as claimed in claim 1 wherein the pin sleeves are each fixedly connected to the container base by a mechanical means.
 4. The pellicle container as claimed in claim 1 wherein the pellicle supporting pinn is provided with an elastomeric member at the point, with intervention of which the pin comes into contact with the cavity in the pellicle frame
 6. 5. The pellicle container as claimed in claim 2 wherein the container base and the covering body made from a plastic resin have a surface resistivity not exceeding 1×10¹² ohms. 